For the first time we present temperature-dependent dc conductivities of a series of mixed alkali glasses with three types of alkali ions and activation energies determined thereof. The studied glasses are alkali borate glasses of type xLi(2)O(0.2-x)Na2O center dot 0.1K(2)O center dot 0.7B2O(3) with x=0, 0.04, 0.08, 0.10, 0.12, 0.16 and 0.20. The new results confirm our previous prediction presented in Solid State Ionics, Volume 176, Issues 9-10 (2005) 921-927 that the mixed cation effect is more pronounced in glasses with three types of cations (ternary mixed alkali glasses) than in those with two types of cations (binary mixed alkali glasses). (c) 2005 Elsevier B.V. All rights reserved.